Two part casing for trigger switch with one part mounting all switch contact members

ABSTRACT

The parts of an electric switch are contained within a two-part insulating casing in which a trigger member slides and operates an over-center mechanism to impart a snap action movement to a yoke which causes a movable contact carrier to operate bridging contacts. Sets of fixed contacts are engaged and disengaged by different bridging contacts with one bridging contact always remaining in contact with one fixed contact of its set. The fixed contacts are stamped from sheet metal and are mounted edgewise in separate slots in the casing. All of said fixed and bridging contact members are mounted in one of said casing parts.

United States Patent 1191 Johnson Oct. 16, 1973 [54] TWO PART CASING FORTRIGGER 3,673,365 6/1972 Schadow 200/16 D x SWITCH WITH N T MOUNTING ALL3,548,276 12/1970 Gross 318/380 X SWITCH CONTACT MEMBERS 3,588,4116/1971 Milcoy 200/ 157 [75] Inventor: David W. Johnson, Newington,

Conn Primary Examiner-Robert K. Schaefer w Assistant ExaminerRbcrt A.Vanderhye [73] Asslgnee: Arrow-hart, Inc., Hartford, Conn. Atmmey winiamE Sonnekalb, In [22] Filed: Apr. 24, 1972 [21] App]. No.: 246,951 [57]ABSTRACT The parts of an electric switch are contained within a U-S. D,two-part insulating casing in which a trigger member 200/166 CT slidesand operates an over-center mechanism to imf Clm H0111 13/08, H01111/58, H0111 13/30 part a snap action movement to a yoke which causes aFleld of Search 76, C, movable ontact carrier to operate contacts 200/16D, 166 BH, 166 CT Sets of fixed contacts are engaged and disengaged bydifferent bridging contacts with one bridging contact References Citedalways remaining in contact with one fixed contact of UNITED STATESPATENTS its set. The fixed contacts are stamped from sheet 2,776,348 11957 Korry 200/76 metal and are mounted edgewise in Separate Slots in3,290,463 12/1966 Johnson 200/76 x the g- All o i fi and bn'dgingContact members are mounted in one of said casing parts.

7 Claims, 9 Drawing Figures 1 a 3/ li i i I l i 'Q' /33 f 2/ a e 49 D-il I 1 TWO PART CASING FOR TRIGGER SWITCH WITH ONE PART MOUNTING ALLSWITCH CONTACT MEMBERS This invention relates to electric switches forcontrolling the operation of portable electric power-operated hand toolsand more particularly relates to a snap action electric switch having atrigger as an operating member for movable contacts and having fixedcontacts which are engaged and. disengaged by movement of the triggermember and movable contacts to cause encircuiting connections to anelectric :motor for operating it at full power or dynamically brakingthe motor immediately upon disconnecting it from the power lines.

BACKGROUND OF THE INVENTION The patent of T.A.O. Gross U.S. Pat. No.3,548,276 issued Dec. 15, 1970, discloses a circuit suitable for use inconnection with electric power operated portable hand tools fordynamically'braking the motor when the circuit to it from the source ofpower is broken. This circuit contemplates use of a conventional doublepole double throw switch to connect a universal or a series wound motordirectly in series circuit with the power lines in the on position ofthe switch and to brake the connection of the motor to the power linesin off position, while concomitantly connecting the motor winding withthe dynamic braking circuitry.

BRIEF DESCRIPTION OF THE INVENTION According to the invention, the partsof the switch are mounted within a two-part insulating casing containingtwo sets of contacts which are connectable to an electric motor and thepower line by movement of a movable contact in in one position of theswitch. In another position of the switch, the contacts are connected toelectronic circuit components including diodes and a small sizecapacitor which are also contained within the insulating casing and tothe motor to cause dynamicbraking of the motor. An insulating movablecontact carrier carries two bridging contacts each of which bridgeseither a common and one or the i'olhfil of two other contacts of the setas a slidable trigger is moved in and outwardly of the casing andoperates a snap action over-center yoke which causes movement of themovable contact carrier.

It is an object of the invention to provide a novel compacttrigger-operated switch for use in a portable electric power operatedtool utilizing the circuit of said patent or of any other suitabledynamic braking circuit.

Other objects and advantages of the invention will appear as it isdescribed in connection with the accompanying drawing.

Another object is to provide a novel construction of a snap actiondouble-pole double throw, triggeroperated switch, which may beeconomically assembled from economically manufactured parts, andincluding electronic circuit components within a com? pact casing, foruse in a dynamic braking circuit.

In the drawing, FIG. 1 is a side elevation view of a switch embodyingthe invention.

FIG. 2 is a side elevation view with the cover removed and viewed fromthe opposite side from FIG. 1.

FIG. 3 is an end elevation view.

FIG. 4 is a perspective view partly broken away of the contact carrierand one movable contact used in the invention.

FIG. 5 is a section view along line 5-5 of FIG. 4.

FIG. 6 is an exploded perspective view of the upper contact and terminalmembers.

FIG. 7 is an exploded perspective view of the lower contacts andterminal members.

FIG. 8 is a detailed view showing in side elevation the end terminalmember.

FIG. 9 is a schematic view of the switch contacts and terminals whenused in a dynamic braking circuit.

Referring to the drawing, two mating casing halves 10 and 20 are moldedof insulating material into convenient elongated tapered rectangularshape with hollowed-out and recessed interiors to accommodate the partsof the switch mechanism when the halves are put together. 7

At one end of the casing guideways 21 are provided for a rectilinearlyslidable trigger member 30 which has a finger engaging portion 30a ofcommon shape exterior to the casing, and a portion 30b extending intothe casing and slidable in the guideways of the casing halves.

A coiled compressed biasing spring 21 seats at one end in a recess inthe finger portion 30 of the trigger while its opposite end pressesagainst the casing to bias the trigger to off position.

To operate the movable parts of the switch an overcenter coiledcompression spring 33 engages at one end with a nub 30c on the inner endof the trigger and seats at its other end on the transverse portion of aU-shaped sheet metal yoke 31. The yoke is pivotally mounted by outwardlyextending trunnions seated in aligned bearing recesses in the casinghalves. The transverse portion of the yoke engages a longitudinallyslidable contact carrier 35 made of molded insulating material which isT-shaped in cross-section and extends parallel to the travel of thetrigger and adjacent the inner portion 30b of the trigger. The contactcarrier 35 is guided in its sliding movement by engagement with thecasing and the fixed contacts hereinafter described.

The contact carrier has a guide part 35a and a contact carrying part 35cperpendicular to the guide part, the carrier part 350 having oppositelyfacing parallel surfaces facing the cover part 10 and the base part 20of the casing. Seated on each of these surfaces is a stamped metalmovable bridging contact 37, 39, respectively, of flattened dumbbellshape having domed contact buttons 37c, 390 at each end. The contactbuttons are adapted to engage different fixed contacts (as hereinafterdescribed) as the carrier 35 is moved by the yoke 31 as the yoke swingsbetween off and on positions when the trigger is finger pressed in andreturns outwardly when released. In order that the movable contacts mayresiliently engage the various fixed contacts and be biased toward them,two coiled compression springs 38 are provided in two spaced cylindricalbores 35b or recesses beneath the contact buttons 35c.

The fixed contacts for engagement and disengagement by the movablebridging contacts are mounted in the base half 20 of the casing inspaced positions as will now be described.

The fixed contacts are located in two levels in parallel planes. Onlyfor convenience in reference, the contacts in these levels will bereferred to as upper and lower contacts simply to identify them, itbeing obvious that the invention is not limited to higher or lowerlocation of the contacts with respect to each other or to the casingparts.

The contact members 40, 50, 60, 70, 80 and 90 are all stamped from sheetmetal into the various shapes illustrated in FIGS. 6 and 7 and aremounted edgewise in separate slots molded in the base half of thecasing. The contour of each slot is complementary to the edgewisecontour of the member which it receives. Some of the members have flatterminal extensions which project through apertures in the flat floor ofthe base half 20 as described below.

Viewing FIG. 2, the second, fourth and sixth members 40, 50 and 60 eachhave flat central body portions as may be seen in detail in FIG. 7. Fromeach, a finger extends towards the movable contact carrier 35 thusproviding upper contacts 43, 53, 63 which have flat under edge surfaceslying in the same plane and adapted to be engaged by the bridgingcontact 37 as it is slid to and fro by movement of the carrier 35 unclerinfluence of the yoke 30. 7

.Members 40 and 50 on the edges opposite the contact fingers each have aterminal lug, 41 and 56 respectively, extending from its inner edgethrough apertures in the base half 20.

The first, third and fifth members 70, 80 and 90, each have flat centralbody portions as may be seen in detail in FIG. 6. From each, a fingerextends toward the movable contact carrier thus providing lower contacts72,82 and 92, which have flat upper edge surfaces lying in the sameplane and adapted to be engaged by the bridging contact 39 as it is slidto and fro by movement of the carrier 35 under the influence of yoke 30.Members 70 and 80 on the opposite contact fingers each have terminallugs, 73 and 84 respectively, extending from its inner edge throughapertures in the base half 20. t

The members'60 and 90 may have terminal portions but do not require themin the usage for which the disclosed embodiment is intended.

The movable contact members 37 and 39 are of such length that theirdome-shaped contact portions 37c and 39c, respectively, are spaced-aparta distance equal to the spacing of the contact fingers. Specifically andfor example, the upper movable contact 37 has its contact buttons spacedapart the same distance as the upper fixed contacts 43 and 53; and thisdistance is the same as the distance between the contact fingers53 and63. Thus, when the switch is in the off position as illustrated in FIG.2, contact 37 bridges the upper contact fingers 63 and 53. When theswitch is moved into the on position, the movable contacts will slideinto position where it will engage and bridge the contact fingers 43 and53.

Likewise, the lower contact 39 in the off position of FIG. 2 will bridgethe lower contact fingers 92 and 82; and when moved into the on positionthe lower contact 39 will bridge the lower contact fingers 82 and 72.

From the foregoing, it will be clear that the switch can occupy only twopositions even though the trigger may be in transit between its fullydepressed or fully released positions. Movement of the trigger will notbecome effective to change the'position of the movable contact members37,39 unitl the over-center spring 33 is moved through an over-centerposition in respect to the yoke 31 as the trigger is actuated. As theovercenter position is passed through, the yoke will move the contactcarrier and bridging-contacts with a snap action. 1

As will now be described, the fixed contacts 53, 63 and 82, 92 havecircuit connections to electronic circuit components for dynamic brakingof a motor which may be connected to the switch terminals, whilst thefixed contacts 72, 73 are connected respectively to one power line andto one side of the motor A armature. In the off position contact 72 isnot engaged by the bridging contact 39, in consequence of which thepower to the motor is cut off and only the braking circuitry isconnected operatively. On the other hand, while the braking circuitry isconnected operatively (in the off position) it is ineffective after themotor armature has stopped turning.

One use of the invention is in connection with the circuit of the abovementioned Gross U.S. Pat. No. 3,548,276. When so used, a capacitor C ismounted within the casing near the lower end and is connected at itsnegative end to a terminal 100 made of stamped sheet metal and mountedin the end of the base 20 of the casing in a slot similarly to the otherterminal and contact members. The terminal member 100 has a terminal lug101 extending through an aperture in the casing wall for externalconnection thereto of an external resistor (not shown) in accordancewith said U.S. Pat. No. 3,548,276.

Also connected to the terminal 100 isthe anode of a diode D-l whosecathode is connected to the cathode of another diode D-2 and to thepositive side of the capacitor C and to the contact member 60 by wireswhich are soldered intoa notch 62 formed in the upper edge of the member60.

The anode of the diode D-2 is connected to the contact 80. To theterminal 84 of the contact is also connected one end of the field orstator winding S of the motor, while the other end of that winding isconnected to terminal 56 of the contact 50.

A shunt connection 49 consisting of flexible highly conductive bowedmetallic strips positioned face to face with their ends in notches inthe contacts 40 and connects those contacts electrically.

From the foregoing, it will be observed that by the edgewise mounting ofthe contact and terminal members in slots in base portion 20 of thecasing, a considerable number of contact and'terminal members can becompactly arranged in insulated relation. Also by-having the contactfingers in two levels a single bridging I contact carrier can beconveniently positioned with bridging contacts mounted thereon in thedifferent planes in which each contact member must move to bridge itsset of fixed contacts. In addition to the foregoing, the compactarrangements of the fixed and movable contact members permits the use ofan over-center type of action in a unit. It is particularly important,when the invention is applied to a circuit such as that of U.S. Pat. No.3,548,276, that the movable contacts disconnect the power line from the.motor prior to the encircuiting of the braking circuitry and also thatthe switch and its contained components be small enough to be readilyand conveniently mounted within the handle of a portable power-operatedtool such as a saw.

Many modifications within the scope of the invention will occur to thoseskilled in the art. Therefore, the invention is not limited to theprecise form herein'described.

I claim:

1. An electric switch comprising an insulating casing made of twocooperating parts recessed to cooperatively receive and positionconductive switch and circuit elements, a trigger member slidable in acavity at one end of said casing, a yoke member pivotally mounted insaid casing and operable between two positions, an over-center springconnecting said trigger member and said yoke imparting snap actionmovement to said yoke incident to movement of said trigger member, amovable contact carrier operated to and fro by said yoke member in thesame direction as said trigger member, a plurality of bridging contactmembers mounted on said carrier in insulated relation, a plurality ofsets of fixed contacts engageable and disengageable by differentbridging contact members, all said fixed and bridging contact membersbeing mounted in one of said casing parts, said fixed contacts beingstamped from sheet metal and mounted edgewise in separate slots in saidcasing in generally parallel relationship to one another and in adirection transverse to the direction of movement of said movablecontact members, said bridging contact members each remaining inengagement with one of the fixed contacts of its set in both positionsof said yoke.

2. A switch as claimed in claim 1 in which said sets of fixed contactshave the contact surfaces of the sets in spaced planes.

3. A switch as claimed in claim 2 in which said contact carrier hasoppositely facing contact surfaces on which said bridging contactmembers are supported, spring means supported in said carrierresiliently supporting at least one of said-bridging contacts.

4. An electric switch adapted for dynamically braking an electric motor,comprising an insulating casing made of two cooperating parts recessedto cooperatively receive and position conductive switch and circuitelements, a trigger member slidable in a cavity at one end of saidcasing, a yoke member pivotally mounted in said casing and operablebetween two positions, an over-center spring connecting said triggermember and said yoke imparting snap action movement to said yokeincident to movement of said trigger member, a movable contact carrieroperated to and fro by said yoke member in the same direction as saidtrigger member, a plurality of bridging contact members mounted on saidcarrier in insulated relation, a plurality of sets of fixed contactsengageable and disengageable by different bridging contact members, allsaid fixed and bridging contact members being mounted in one of saidcasing parts, said other casing part having recesses to guide themovement of said trigger member, said fixed contacts being stamped fromsheet metal and mounted edgewise in separate slots in said casing ingenerally parallel relationship to one another and in a directiontransverse to the direction of movement of said movable contact members,said bridging contact members each remaining in engagement with one ofthe fixed contacts of its set in both positions of said yoke, and aseparate terminal member mounted in a separate slot in said casing andextending through a wall thereof, a capacitor in said casing connectedto said separate terminal and to one of said contacts, and two diodes insaid casing having opposite ends thereof connected to said one contact,one of said diodes being also-connected to said separate terminal, andthe other diode being connected also to one of said contact and terminalmembers.

5. A switch as claimed in claim 4 in which said sets of fixed contactshave the contact surfaces of the sets in spaced planes.

6. An electric switch comprising an insulating casing made of twocooperating parts recessed to cooperatively receive and positionconductive switch and circuit elements, a trigger member slidable in acavity at one end of said casing, a yoke member pivotally mounted insaid casing and operable between two positions, an over-center springconnecting said trigger member and said yoke imparting snap actionmovement to said yoke incident to movement of said trigger member, amovable contact carrier operated to and fro by said yoke member in thesame direction as said trigger member, a plurality of bridging contactmembers mounted on said carrier in insulated relation, said contactcarrier having oppositely facing contact surfaces on which said bridgingcontact members are supported, and spring means supported in saidcarrier resiliently supporting at least one of said bridging contacts, aplurality of sets of fixed contacts engageable and disengageable bydifferent bridging contact members, all said fixed and bridging contactmembers being mounted in one of said casing part, said other casing parthaving recesses to guide the movement of said trigger member and saidyoke member; said fixed contacts being stamped from sheet metal andmounted edgewise in separate slots in said one casing part in generallyparallel relationship to one another and in a direction transverse tothe direction of movement of said movable contact members, said bridgingcontact members each remaining in engagement with one of the fixedcontacts of its set in both positions of said yoke.

7. A switch as claimed in claim 6 in which a plurality of said fixedcontacts have terminal portions extending through apertures in the wallof said casing.

1. An electric switch comprising an insulating casing made of twocooperating parts recessed to cooperatively receive and positionconductive switch and circuit elements, a trigger member slidable in acavity at one end of said casing, a yoke member pivotally mounted insaid casing and operable between two positions, an over-center springconnecting said trigger member and said yoke imparting snap actionmovement to said yoke incident to movement of said trigger member, amovable contact carrier operated to and fro by said yoke member in thesame direction as said trigger member, a plurality of bridging contactmembers mounted on said carrier in insulated relation, a plurality ofsets of fixed contacts engageable and disengageable by differentbridging contact members, all said fixed and bridging contact membersbeing mounted in one of said casing parts, said fixed contacts beingstamped from sheet metal and mounted edgewise in separate slots in saidcasing in generally parallel relationship to one another and in adirection transverse to the direction of movement of said movablecontact members, said bridging contact members each remaining inengagement with one of the fixed contacts of its set in both positionsof said yoke.
 2. A switch as claimed in claim 1 in which said sets offixed contacts have the contact surfaces of the sets in spaced planes.3. A switch as claimed in claim 2 in which said contact carrier hasoppositely facing contact surfaces on which said bridging contactmembers are supported, spring means supported in said carrierresiliently supporting at least one of said bridging contacts.
 4. Anelectric switch adapted for dynamically braking an electric motor,comprising an insulating casing made of two cooperating parts recessedto cooperatively receive and position conductive switch and circuitelements, a trigger member slidable in a cavity at one end of saidcasing, a yoke member pivotally mounted in said casing and operablebetween two positions, an over-center spring connecting said triggermember and said yoke imparting snap action movement to said yokeincident to movement of said trigger member, a movable contact carrieroperated to and fro by said yoke member in the same direction as saidtrigger member, a plurality of bridging contact members mounted on saidcarrier in insulated relation, a plurality of sets of fixed contactsengageable and disengageable by different bridging contact members, allsaid fixed and bridging contact members being mounted in one of saidcasing parts, said other casing part having recesses to guide themovement of said trigger member, said fixed contacts being stamped fromsheet metal and mounted edgewise in separate slots in said casing ingenerally parallel relationship to one another and in a directiontransverse to the direction of movement of said movable contact members,said bridging contact members each remaining in engagement with one ofthe fixed contacts of its set in both positions of said yoke, and aseparate terminal member mounted in a separate slot in said casing andextending through a wall thereof, a capacitor in said casing connectedto said separate terminal and to one of said contacts, and two diodes insaid casing having opposite ends thereof connected to said one contact,one of said diodes being also connected to said separate terminal, andthe other diode being connected also to one of said contact and terminalmembers.
 5. A switch as claimed in claim 4 in which said sets of fixedcontacts have the contact surfaces of the sets in spaced planes.
 6. Anelectric switch comprising an insulating casing made of two cooperatingparts recessed to cooperatively receive and position conductive switchand circuit elements, a trigger member slidable in a cavity at one endof said casing, a yoke member pivotally mounted in said casing andoperable between two positions, an over-center spring connecting saidtrigger member and said yoke imparting snap action movement to said yokeincident to movement of said trigger member, a movable contact carrieroperated to and fro by said yoke member in the same direction as saidtrigger member, a plurality of bridging contact members mounted on saidcarrier in insulated relation, said contact carrier having oppositelyfacing contact surfaces on which said bridging contact members aresupported, and spring means supported in said carrier resilientlysupporting at least one of said bridging contacts, a plurality of setsof fixed contacts engageable and disengageable by different bridgingcontact members, all said fixed and bridging contact members beingmounted in one of said casing part, said other casing part havingrecesses to guide the movement of said trigger member and said yokemember; said fixed contacts being stamped from sheet metal and mountededgewise in separate slots in said one casing part in generally parallelrelationship to one another and in a direction transverse to thedirection of movement of said movable contact members, said bridgingcontact members each remaining in engagement with one of the fixedcontacts of its set in both positions of said yoke.
 7. A switch asclaimed in claim 6 in which a plurality of said fixed contacts haveterminal portions extending through apertures in the wall of saidcasing.